Two identical nuclei `A` and `B` of the same radioactive element undergo `beta^(-)` decay. `A` emits a `beta^(-)` particle and changes to `A'`. `B` emits a `beta^(-)` particle and then a `gamma`-photon immediately afterwards, and changes to `B`.

Options

A. A' and B' have the same atomic number and mass number
B. A' and B' have the same atomic number nut different mass numbers
C. A' and B' have different atomic numbers but the same mass number
D. A' and B' are isotopes.

Answer

A